Particle throwing apparatus



Jan. 10, 1967 WU G, R ET AL 3,296,746

PARTICLE THROWING APPARATUS 2 Sheets-Sheet 1 Original Filed April 27, 1962 INVENTORS ATTORNFXQ WWW Jan. 10, 1967 J. E. BOWLING, JR. ET AL PARTI OLE THROWING APPARATUS Original Filed April 27, 1962 2 Sheets-Sheet 2 INVENTORS Jose ph E. Bowlin .Jri.

George W. POI/Ire ATTORNEYS United States Patent 6 "3,296,746 Patented Jan. 10, 1967 4 Claims. (or. 51-9) This application is a division of co-pending application Serial No. 190,725, filed April 27, 1962, now abandoned, which in turn is a continuation-in-part of application Serial No. 753,530, filed August 6, 1958, now abandoned.

The present invention relates to a particle throwing apparatus, in particular to such an apparatus of the type shown in US. Patent 2,732,666, granted January 31, 1956. Such apparatus forcefully projects a directional stream of particles for impingement against work pieces that are to be cleaned, peened or otherwise treated by the articles.

Among the objects of the present invention is the provision of novel constructions for such apparatus so that they are simpler and more reliable to use and maintain.

The above as well as additional objects of the present invention will be more clearly understood from the following description of several of its exemplifications, reference being made to the accompanying drawings where- FIG. 1 is a broken-away perspective in section of one embodiment of this invention; and

FIGS. 23 are views showing modifications of the present invention.

According to the present invention, a particle throwing apparatus has a single disc rotor with a fiat working face. A number of rectangular shaped particle throwing vanes are radially supported on the face with their inner ends spaced from its center and with the faces of the vanes lying perpendicular to the disc face so that rotation of the rotor causes particles to be thrown radially outward from the forward faces of the vanes when such particles are supplied to the center of the rotor face. The rotor face has vane holders to which the vanes are se cured. The rotor, vanes and vane holders can be integral portions of a single casting, and all have a surface coating with a hardness of at least 750 Knoop.

The surface coating is very effectively cemented in place to give a long-wearing construction, but it can also be molded in place as by lining the walls of a mold with a layer of powdered tungsten carbide or the like. The pouring into a mold so lined, of the molten metal that forms the body of the structure will cause the powdered lining to become integrated with the surface of the cast metal.

An integral combination of vanes, vane holders and rotor or the so-called monolithic arrangement, is of particular advantages when used to project particles of relatively low density such as the so-called soft abrasives. Typical soft abrasives include ground corn cobs, ground shells of walnuts, ground apricot pits, rice hulls, sawdust, and the like. For such use the rotor and vane combination need not be as massive as when used to propel steel particles or the like, where there is a relatively rapid erosion of the surfaces the steel particles engage as they move through the throwing apparatus. Soft abrasive vanes as much as 5 inches wide measured in a direction parallel to the axis of the rotor, can accordingly be used in the above monolithic combination where the vanes themselves are as thin as /1. inch and they are only secured to the rotor at one of their side edges. Also the rotor face can be grooved to provide a simply labyrinth type of seal for the purpose of reducing leakage of abrasive particles away from the throwing path they are to be directed to.

A soft abrasive apparatus in accordance with the present invention can have an unprotected spindle on which the rotor is journaled so that the relatively expensive housing used with heavy-duty throwing wheels is not needed.

Also for soft abrasives it is preferable as another feature of the present invention to supply the soft abrasive to the throwing wheel from a hopper which has its upper portion at least about half covered to reduce intake of air into the throwing wheel when it is rotated.

Where the runnerhead is used with soft abrasive or for light duty, it can be directly clamped around the end of the spindle on which it is journaled by providing it with a central aperture which is tapered, and using between the central aperture and the spindle end an intervening bushing tapered to mate with the taper of the aperture. When used with a monolithic wheel as referred to above in connection with soft abrasive applications, this gives an overall construction which is very simple to manufacture.

FIG. 1 shows a throwing wheel assembly which is very effective for throwing the soft abrasive particles. The general construction of FIG. 1 is much like that of parent application S.N. 190,725, filed April 27, 1962 and the various differences are pointed out as follows. The spindle 10 is not surrounded by a housing and its bearings 214 can be completely exposed. These bearings can be automatically lubricated through lines 215 that are connected to a lubricant supply pump. Runner head 218 is integrally formed as one piece with vanes 240 and is directly secured to the spindle without the use of an intervening spindle flange. Impeller 262 is aligned by the use of a pair of attaching screws 264. Impeller cage 270 has its inner end open and in labyrinth sealing engagement with a groove 296 in the outer face of the rotor. A single rotor sealing ring 256 between the rotor and the rear of the housing is all the sealing that is needed in this location. Also the spout is connected to a particle supply hopper 289 that is more than half covered by a lid 291 to reduce the intake of air into the wheel. Without such covering the wheel centrifugally blows air with an etficiency that develops substantial suction in the spout and the horsepower used for pumping air is thus lost for throwing abrasive.

The spout 288 is illustrated as held in place against the impeller cage 270 by a quick-acting toggle clamp 293, while one or more additional quick-acting toggle clamps 295 lock the lip of the cage to the housing. Removal of spout only requires operation of clamp 293, but adjustment of the cage call for manipulation of all the clamps. Manually operated clamps of this type are, however, simple and rapid to operate.

In the construction shown in FIG. 1, runnerhead 218 has an internal opening 30 which is tapered and fitted over a bushing 31 that has an outer surface provided with a mating taper. The inner surface of the bushing 31 can be cylindrical to fit against a correspondingly shaped portion of the spindle. The resulting overall construction is accordingly very simple to manufacture.

FIG. 2 shows a further modified construction in which a rotor assembly 618 is integrally cast with vane portions 640 as well as with additional bracing, such as that shown at 630. The particle engaging surface 642 of vane portions 640 can then be provided, if desired, with a particularly abrasion-resistant covering.

A highly suitable abrasion-resistant composition is tungsten carbide particles bonded together by metal. A mixture of tungsten carbide particles and a bonding powder of metallic iron, cobalt, nickel, titanium or the like, is projected through an oxyhydrogen or oxyacetylene flame onto the surface 042. The bonding metal powder fuses in the flame and remains molten until the projected streams reaches surface 642. There it solidifies and holds the tungsten particles in place against the metal base of vane 640. Coating thicknesses of of an inch are all that is needed although thicknesses of 5 to A inch can also be used. It is desirable after the coating is applied to heat the entire coating as by a torch or in a furnace to a temperature sufficient to cause the bonding powder to sinter more securely to the base as well as to the tungsten carbide particles. A temperature of 1900 F. is sufiicient for this purpose along with a sintering time of about 5 to 30 minutes. Other carbides such as boron carbide, zirconium carbide and tantalum carbide can be used in place of tungsten carbide. Any of these materials will provide coatings having a hardness of at least about 800 Knoop (approximately Rockwell 62 on the C scale) even when the weight ratio of bonding metal to carbide is 1.5. Higher proportions of carbide in the final products are preferred. Hardness of at least 750 Knoop are desired.

Other long-wearing coatings suitable for use according to the persent invention are ceramic materials such as alumina, zirconia, thoria, etc. These can be readily applied by sintering or cementing a layer of such particles in place.

Instead of spraying the coating in place, a protective layer can be performed as by sintering together the above carbide particles with finely divided bonding metal in a mold of graphite for example. The preformed covering can then be secured in position as by cementing with epoxy resin cement, as by having the parts clamped together with a thin resin layer between them, and kept so clamped while the resin is cured, generally as by heating to 250-300" F. for a half hour. The epoxy resin cement can be applied in the form of liquid (at normal temperatures) or as a solid which must be fused beforehand.

A covering cemented on in the above manner can be fairly readily removed and replaced. Applying a torch flame to the covering until the cement reaches a temperature at which it decomposes, will loosen the covering so that it can be pried ofi or knocked off with a few hammer blows. The base metal can then be cleaned as by wire brushing and the cementing then repeated with a fresh coating. The above heating will not change the strength of the base even if it is sensitive to heat treatment. Where it is not so sensitive, the entire coated base can be placed in an oven to cause the resin to decompose.

The abrasion-resistant coatings need not be applied as a continuous unbroken layer. For example, the layer can be subdivided into a plurality of small areas having corresponding configurations, and corresponding small coating portions can be cemented to each area. This forms a mosaic-like product which gives excellent results. To help reduce excessive fractures at the coating joints in such a mosaic, cement can be worked into these joints.

Another effective technique for providing the extremely abrasion-resistant surfaces, is to cast the vanes with or without the vane holders and the runnerhead, from molds which are lined with powdered or presintered abrasionresistant material. A powdered lining of this type can be provided in coherent form as a baked insert molded with a small amount of resin. The pouring of the molten metal into the mold followed by the solidification of that metal will cause the abrasion-resistant lining to become adherently united to the solidified metal, and will also act to sinter the abrasion-resistant particles to each other where they are not so Presintered.

Boron carbide, silicon carbide and other hard materials can also be sintered together without a hinder, or with very little binder to make facing members that can be cemented or mechanically secured in place as by wedging or bolting.

The preformed coating can also be sintered in place either by a second sin-tering operation, or else the first sintering operation can be carried out directly on the vane sections 649. Furthermore, the abrasion-resistant coating can be welded or brazed in placed.

FIG. 3 shows a further modification in which the vanes are made integral with the vaneholders and a plurality of the thus formed integral units represented at 739, are individually mounted on the rotor 518. Even the construction of such a less complicated unit as the vane and vane holder assembly can be simplified by making it of material that is not too abrasion resistant, and providing it with an abrasion-resistant coating or insert 740 in those places where the particles to be thrown by the apparatus come in most violent contact.

Gbviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A particle throwing apparatus for soft abrasive particles having a runnerhead, a number of relatively thin sheet-like throwing vanes radially disposed on the working face of said runnerhead with their ends spaced from its center and with the faces of said vanes perpendicular to said working face whereby rotation of said runnerhead causes particles to be thrown radially outward from the forward faces of said vanes when such particles are supplied to the center, said runnerhead and vanes being integral portions of a single casting, said runnerhead being secured to an unprotected spindle, said spindle being mounted in exposed bearings, an impeller at the center of said runnerhead secured to said spindle, and a slotted impeller cage being between said impeller and said ends of said vanes.

2. A particle throwing apparatus for soft abrasive particles having a runnerhead, a number of sheetlike throwing vanes radially disposed on the working face of said runnerhead with their ends spaced from its center and with the faces of said vanes perpendicular to said working face whereby rotation of said runnerhead causes particles to be thrown radially outward from the forward faces of said vanes when such particles are supplied to the center, said runnerhead and vanes being integral portions of a single casting, said runnerhead being secured to an unprotected spindle, said spindle being mounted in exposed bearings, said runnerhead being a tapered opening, a correspondingly tapered bushing being on said spindle, and said runnerhead being secured on said bushing whereby said runnerhead is secured directly to said spindle by means of said bushing.

3. A particle throwing apparatus for soft abrasive particles having a runnerhead, a number of sheet-like throwing vanes radially disposed on the working face of said runnerhead with their ends spaced from its center and with the faces of said vanes perpendicular to said working face whereby rotation of said runnerhead causes particles to be thrown radially outward from the forward faces of said vanes when such particles are supplied to the center, said runnerhead and vanes being integral portions of a single casting, said runnerhead being secured to an unprotected spindle, said spindle being mounted in exposed bearings, an annular groove being in said runnerhead face adjacent the inner ends of each vane, an impeller being fitted in the central space between the inner ends of the vanes, and a slotted impeller case surrounds the impeller and extends into the groove and forms a labyrinth seal with respect to said runnerhead face.

4. A particle throwing apparatus for soft abrasive particles having a runnerhead, a number of sheet-like throwing vanes radially disposed on the working face of said 5 runnerhead with their ends spaced from its center and with the faces of said vanes perpendicular to said Working face whereby rotation of said runnerhead causes particles to be thrown radially outward from the forward faces of said vanes when such particles are supplied to the center, said runnerhead and vanes being integral portions of a single casting, said runnerhead being secured to an unprotected spindle, said spindle being mounted in exposed bearings, a particle supplying feed hopper 10 being connected to discharge into the central space between said vanes, and the hopper has its upper portion at least about half covered to reduce intake of air into the apparatus when the rotor is rotated.

References Cited by the Examiner UNITED STATES PATENTS Beeg 519 Keefer 51-9 Alexander 519 Unger 519 Guendling 519 Cockrum 76101 Unger 519 Eckler et a1. 519 Turnbull 519 Gossard 519 Walk et a1 51-9 X LESTER M. SWINGLE, Primary Examiner. 

1. A PARTICLE THROWING APPARATUS FOR SOFT ABRASIVE PARTICLES HAVING A RUNNERHEAD, A NUMBER OF RELATIVELY THIN SHEET-LIKE THROWING VANES RADIALLY DISPOSED ON THE WORKING FACE OF SAID RUNNERHEAD WITH THEIR ENDS SPACED FROM ITS CENTER AND WITH THE FACES OF SAID VANES PERPENDICULAR TO SAID WORKING FACE WHEREBY ROTATION OF SAID RUNNERHEAD CAUSES PARTICLES TO BE THROWN RADIALLY OUTWARD FROM THE FORWARD FACES OF SAID VANES WHEN SUCH PARTICLES ARE SUPPLIED TO THE CENTER, SAID RUNNERHEAD AND VANES BEING IN- 